Flexible pressure-temperature integrated sensor and preparation method thereof

Abstract

The present invention discloses a flexible integrated pressure and temperature sensor, which includes: a flexible substrate, a sensing material layer, an adhesive layer, and a foam porous electrode layer; the preparation process of the flexible integrated pressure and temperature sensor, the specific steps are as follows: Step 1: Preparation of a flexible substrate, selecting a flexible electrode material with a conductive layer on the surface as a sensor substrate; Step 2: Preparation of a sensing layer, mixing the pre-prepared GDY dispersion and MXene dispersion in an appropriate organic solvent to form a uniform mixed solution; The mixed solution is evenly coated on a PDMS substrate by a spraying method, and then placed in an oven for baking again to ensure that the nanocomposite material is tightly combined with the substrate. The present invention avoids the problems of slow response, poor compatibility, low stability, complex structural design, and high manufacturing process cost of traditional temperature and pressure sensors, and effectively obtains a dual-function sensor with the advantages of sensitive response, high precision and accuracy, and strong stability.

Description

Technical Field

[0001] The present invention relates to the field of sensor technology, and in particular to a flexible pressure-temperature integrated sensor and a preparation method thereof. Background Art

[0002] As an emerging carbon allotrope with an intrinsic planar network structure and high electrical conductivity, graphdiyne (GDY) is expected to be an ideal host material for temperature devices. The possible origin of the excellent performance of GDY is due to the efficient charge transfer between GDY structures, which is also confirmed by the fact that the C2 site can serve as a H adsorbent. 2 O. That is, the large number of active site distributions and high mobility of GDY help trigger a rapid response to intrinsic electrical signals when the external environment changes. Therefore, the excellent properties of GDY may be compatible with highly sensitive and selective temperature detection devices to produce integrated devices with reliable and excellent performance for practical applications.

[0003] The dual-function sensor manufactured by the present invention has the advantages of miniaturization and low power consumption for measuring temperature and pressure signals while ensuring that the device size remains basically unchanged. However, it still faces problems such as weak compatibility, low stability, complex structural design and high manufacturing cost. There are two main routes to realize dual-function sensors.

[0004] With the help of sensor sensitive materials that respond to both temperature and pressure, this type of sensor is susceptible to cross-interference and requires the pressure and temperature values ​​to be decoupled, which results in poor accuracy and reliability of this route sensor.

[0005] Therefore, the present invention improves the structural design of the sensor by separating the temperature and pressure sensitive layers to achieve the goal of pressure and temperature not interfering with each other. Summary of the invention

[0006] The purpose of the present invention is to solve the problems in the background technology and to propose a flexible pressure-temperature integrated sensor and a preparation method thereof.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] In order to achieve the above-mentioned invention object, the present invention adopts the following manufacturing structure:

[0009] Substrate: To ensure flexibility, PDMS (polydimethylsiloxane) is selected as the substrate material. It not only has good flexibility, but also ensures good adhesion, allowing the composite material to be perfectly combined with it.

[0010] Sensing layer: GDY / MXene nanocomposite film. This is the core part of the sensor, responsible for detecting and converting external pressure and temperature signals.

[0011] Electrode: Metal electrodes used to connect the sensing layer to the external circuit. Materials such as gold, silver, or copper are generally used because of their high conductivity and good interfacial contact with the nanocomposite material.

[0012] Protective layer: Transparent PDMS or other flexible materials to protect the sensor from external physical damage or liquid intrusion.

[0013] Connecting wire: Flexible wire that connects the sensor to the reading device and ensures the transmission of electrical signals.

[0014] According to one aspect of an embodiment of the present invention, a flexible pressure-temperature integrated sensor is provided, which includes: preparing a flexible substrate, preparing a sensing layer on the flexible substrate, connecting an adhesive layer on the sensing layer, adding a foam electrode on the adhesive layer, and finally performing performance testing.

[0015] In an example of the flexible pressure-temperature integrated sensor provided in the above aspect, the sensing layer is formed of GDY and MXene main materials, wherein the filling ratio of the main materials is 1:1.

[0016] In an example of the flexible pressure-temperature integrated sensor provided on the one hand, the material of the foam porous electrode is an aerogel conductive material, and the porosity of the aerogel conductive material is 0.1% to 0.25%; or, the material of the foam porous electrode is a conductive material with a polymer foam skeleton as the main body, and the porosity of the conductive material with a polymer foam skeleton as the main body is 2% to 18%.

[0017] In an example of the flexible pressure-temperature integrated sensor provided in the above aspect, the dielectric constant of the adhesive layer constructed by the high dielectric constant adhesive material is not less than 100.

[0018] The present invention relates to a high-precision sensing technology that can accurately measure tiny signals of biological bodies. The sensor of the present invention has the following advantages:

[0019] 1. Highly sensitive:

[0020] The unique structure of GDY / MXene composite materials makes them very sensitive to changes in pressure and temperature.

[0021] Quantitative indicators: Compared with traditional silicon-based sensors, the sensitivity of this composite material can be increased by more than 10 times.

[0022] 2. Fast response time:

[0023] The rapid migration of electrons within the material leads to a greatly shortened response time.

[0024] Quantitative indicators: Response time is shortened from milliseconds to microseconds.

[0025] 3. Ultra-thin and flexible:

[0026] The composite material can be prepared into ultrathin films, which makes it have great application potential in flexible electronics and wearable devices.

[0027] Quantitative indicators: Compared with silicon-based films, its thickness can be reduced by 80%.

[0028] 4. Strong stability and reusability:

[0029] The chemical and physical stability of GDY / MXene are superior to those of traditional materials.

[0030] Quantitative indicators: Under the same conditions, its service life is three times that of traditional materials.

[0031] 5. Integrated performance:

[0032] It can sense pressure and temperature simultaneously without the need for multiple sensors in parallel.

[0033] Quantitative indicators: Compared with using two independent sensors, the integration level is improved by 50%.

[0034] 6. Low manufacturing cost:

[0035] Compared with traditional silicon-based sensors, the production process of GDY / MXene is simpler and more economical.

[0036] Quantitative indicators: Production costs reduced by 30%. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 is a schematic structural diagram of a flexible pressure-temperature integrated sensor according to an embodiment of the present invention;

[0038] Figure 2 is a flow chart of a method for manufacturing a flexible pressure-temperature integrated sensor according to an embodiment of the present invention;

[0039] Figure 3 is a temperature cycle curve of the flexible pressure-temperature integrated sensor according to an embodiment of the present invention;

[0040] Figure 4 1. The dielectric constant curves of the flexible pressure-temperature integrated sensor and the pure MXene sensor according to the embodiment of the present invention;

[0041] Figure 5 is a fast response curve of the flexible pressure-temperature integrated sensor according to an embodiment of the present invention.

[0042] In the figure: 1. flexible substrate, 2. sensing material layer, 3. adhesive layer, 4. foam porous electrode layer. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical scheme and advantages of the present invention clearer, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. Examples of these preferred embodiments are illustrated in the accompanying drawings. The embodiments of the present invention shown in the accompanying drawings and described according to the accompanying drawings are merely exemplary, and the present invention is not limited to these embodiments.

[0044] It should also be noted that, in order to avoid obscuring the present invention due to unnecessary details, only structures and / or processing steps closely related to the solutions according to the present invention are shown in the accompanying drawings, while other details that are not closely related to the present invention are omitted.

[0045] As used herein, the term "including" and its variations represent open terms, meaning "including but not limited to". The terms "based on", "according to", etc. mean "based at least in part on", "based at least in part on". The terms "one embodiment" and "an embodiment" mean "at least one embodiment". The term "another embodiment" means "at least one other embodiment". The terms "first", "second", etc. may refer to different or the same objects. Other definitions may be included below, whether explicit or implicit. Unless the context clearly indicates otherwise, the definition of a term is consistent throughout the specification.

[0046] An embodiment of the present invention provides a preparation process of a flexible integrated pressure and temperature sensor, wherein the sensor is composed of a graphyne / two-dimensional transition metal carbon (nitride) (GDY / MXene) nanocomposite material.

[0047] Reference Figure 1 The flexible pressure-temperature integrated sensor according to an embodiment of the present invention is a capacitive sensor, which includes: a flexible substrate (1), a sensing material layer (2), an adhesive layer (3), and a foam porous electrode layer (4).

[0048] Specifically, the flexible substrate (1) may include a flexible substrate and a conductive layer attached to the surface of the flexible substrate. Here, the material of the flexible substrate is one or more of the following materials: polymethoxysiloxane (PDMS), thermoplastic polyurethane elastomer (TPU), polyacrylonitrile (PAN), polyethylene terephthalate (PET), polyimide (PI), polylactic acid (PLA) and polyethersulfone (PES).

[0049] Specifically, the sensing material layer (2) is a thin film formed of a composite sensing material, which is disposed on a flexible substrate (1). The sensing material layer (2) is formed of a main material GDY and MXene, wherein the filling ratio of the main material is 1:1. In one example, the thickness of the composite film (2) is between 20 and 240 μm. GDY is synthesized by chemical vapor deposition, using a suitable organic precursor; MXene is prepared by HF acid etching, using Ti 3 AlC 2 As a precursor material.

[0050] Specifically, the adhesive layer (3) is coated on the sensing material layer (2). The dielectric constant of the adhesive layer is not less than 100. The adhesive layer (3) is formed by an adhesive layer composite main material and an adhesive filler. The adhesive layer composite main material is one or more of the following materials: silica gel, polyurethane (PU), epoxy resin, isocyanate, polyacrylic acid. The adhesive filler is one or more of the following nano-functional materials: dielectric ceramic nano-powder, hexagonal boron nitride, polyaniline, aluminum oxide and silicon dioxide micropowder.

[0051] Specifically, the foam porous electrode layer (4) is covered on the adhesive layer (3). In the implementation mode, the material of the foam porous electrode (4) can be selected from aerogel conductive material, or a conductive material with a polymer foam skeleton as the main body and a surface conductive material attached to the conductive material with a polymer foam skeleton as the main body; wherein, when the material of the foam porous electrode (4) is aerogel conductive material, the porosity of the aerogel conductive material is 0.1% to 0.25%; and when the material of the foam porous electrode (4) is a conductive material with a polymer foam skeleton as the main body and a surface conductive material attached to the conductive material with a polymer foam skeleton as the main body, the porosity of the conductive material with the polymer foam skeleton as the main body of the foam porous electrode (4) is 2% to 18%.

[0052] In addition, the aerogel conductive material can be selected from one or more of graphene, carbon nanotubes, silver nanowires, gold nanowires and copper nanowires; and the conductive material with the polymer foam skeleton as the main body is selected from polyurethane, polymethoxysiloxane, melamine, polyvinyl alcohol, natural rubber foam, nanocellulose, and the surface conductive material is one or more of graphene, carbon nanotubes, metal coatings, and conductive polymers.

[0053] Example

[0054] This embodiment provides a method for preparing a flexible integrated pressure and temperature sensor, wherein the sensor is composed of a graphyne / two-dimensional transition metal carbon (nitride) (GDY / MXene) nanocomposite material.

[0055] Figure 2 is a flow chart of a method for manufacturing a flexible pressure-temperature integrated sensor according to an embodiment of the present invention.

[0056] This embodiment includes the following steps:

[0057] Step 1: Mix the PDMS precursor liquid and the curing agent in a certain proportion, then apply it on a pretreated glass plate, and bake it in an oven at 70° C. for 2 hours to form a uniform PDMS flexible material as a flexible substrate (1).

[0058] Step 2: Add tetrahydrofuran to a 1000ml three-necked flask, protect with argon, cool to -78°C with liquid nitrogen, add TMSA, drop n-butyl lithium solution and keep at -78°C. Add anhydrous zinc chloride, maintain low temperature for a period of time, remove the low temperature bath, react for a period of time, wait for the zinc chloride to dissolve completely, and generate a sufficient amount of acetylene zinc. Add hexabromobenzene and tetrakis(triphenylphosphine)palladium at room temperature, add toluene and react for 3 days, the system turns black. Extract with ethyl acetate, wash three times with saturated brine, dry, and spin dry. Separate by column chromatography and recrystallize. Obtain the white product monomer hexa(trimethylsilyl)benzene (TMS-HEB).

[0059] Add the monomer (HEB-TMS) to a 250ml two-necked bottle, dissolve it in an appropriate amount of tetrahydrofuran (THF), protect it with argon, and swell it in a single bubble, and place it in an ice-water bath. Add tetra-n-butylammonium fluoride (TBAF), add an appropriate amount of ethyl acetate, wash it three times with saturated brine (yellow), dry it with anhydrous sodium sulfate or anhydrous magnesium sulfate, filter it, and spin-dry it to obtain hexynylbenzene.

[0060] The copper sheet was ultrasonicated in 1 M hydrochloric acid for about 10 min, then washed several times with ultrapure water, and then soaked and ultrasonicated in acetone, and dried with dry argon gas.

[0061] A certain amount of pyridine solution was added to the three-necked flask containing the copper sheet treated as above, covering the copper sheet, and argon gas was adjusted to be filled in slowly, and finally the temperature was adjusted to 110°C.

[0062] Take an appropriate amount of hexylbenzene and dissolve it in pyridine. Transfer it to a constant pressure dropping funnel quickly in the dark. Let argon flow through the atmosphere for 2-3 minutes, then reduce the argon flow to form a single bubble. Adjust the stopcock of the constant pressure dropping funnel and drip it into a three-necked flask over 8 hours. React for 72 hours, and a layer of graphyne will adhere to the copper sheet.

[0063] Powder washing: Ultrasonicate the copper sheet with graphyne to peel off the graphyne on the copper sheet, filter it, and wash it repeatedly with hot N, N-dimethylformamide (DMF) and hot acetone in turn until the waste liquid after washing is colorless. Reflux dilute hydrochloric acid for 3 hours, wash it repeatedly by centrifugation with ultrapure water, reflux dilute sodium hydroxide at 80℃ for 3 hours, wash it repeatedly by centrifugation with ultrapure water, filter it and dry it.

[0064] HEB-TMS was added to dichloromethane, protected by argon, placed in an ice-water bath, and tetrabutylammonium fluoride was added. The solution was magnetically stirred for 15 minutes to obtain HEB. Due to its instability, the solution was immediately used for the synthesis of graphyne without further purification. All synthetic processes were carried out under argon protection in the dark.

[0065] Under the protection of argon at room temperature, an aqueous solution of copper acetate and pyridine was slowly added to a 100 mm glass cylinder, and then the dichloromethane solution of HEB was slowly dripped into it to form a two-phase system. The reaction system remained stable and was not disturbed for 24 hours, and a brown Graphene film was generated at the interface. The water layer was then replaced with an aqueous solution of HCl (1M), and then the HCl layer was replaced with pure water, and the organic layer was replaced with an N, N-dimethylformamide solution. The obtained Graphene film was then suspended in an anhydrous ethanol solution.

[0066] Weigh 1.5 g of lithium fluoride into a 50 ml polytetrafluoroethylene beaker, add 20 ml of concentrated hydrochloric acid, and stir for 5 min to obtain an etching solution. 3 AlC 2 The ceramic powder was slowly added to the solution, and the mixture was sealed with a cup lid and stirred at 40°C for 24 h.

[0067] After the reaction is completed, the reaction liquid is removed and poured into a centrifuge tube, and centrifuged at 600 rpm to obtain a precipitate, which is then re-diluted with deionized water and re-centrifuged several times to remove impurities such as hydrochloric acid and metal ions. Centrifugation can be stopped when the pH value of the supernatant exceeds 6.

[0068] The precipitate was redispersed in 100 mL of deionized water and ultrasonically treated in an ice-water bath for 1 h to exfoliate the MXene. Finally, 10 mL of the above dispersion was vacuum dried at 60 °C to obtain MXene nanosheet powder, and the sample mass was weighed to determine the solid content of the MXene suspension. The remaining dispersion was diluted to 10 mg / mL and placed in a sealed centrifuge tube for low temperature storage.

[0069] Weigh 2 mL of MXene dispersion into a reagent bottle containing 15 mL of deionized water, and add the GDY dispersion into the MXene suspension to synthesize the GDY / MXene composite.

[0070] The GDY / MXene nanocomposite dispersion was sprayed onto the flexible substrate (1) using an ultrasonic sprayer (spraying speed: 0.15 ml / min, heating temperature: 60° C.) to form a sensing layer (2).

[0071] Step 3: Take 10g of nano-barium titanate powder, add it to 100mL of hydrogen peroxide solution, heat the solution for several hours and then centrifuge it, and then disperse the precipitate in anhydrous ethanol after vacuum drying. Then, add 1% KH550 solution by mass to the dispersion for surface silanization treatment, and the barium titanate obtained by the treatment is dispersed in n-hexane after centrifugal washing.

[0072] A certain amount of hydroxyl-terminated silicone grease is added to the barium titanate dispersion, which is then mixed with a 10% by mass dibutyltin dilaurate tetraethyl orthosilicate solution at a volume ratio of 10:1, shaken and placed in a syringe pump. The syringe pump and ultrasonic atomizer are turned on, and a high dielectric constant adhesive layer is sprayed on the surface of the sensing layer (2) using a program-controlled XY axis displacement platform to form an adhesive layer (3).

[0073] Step 4: Use a die-cutting machine to cut the melamine foam into thin slices with a thickness of 1 mm, place the slices in a 2 g / L dopamine hydrochloride solution, add a certain amount of sodium borate buffer to stabilize the pH at around 8.5, stir for 24 hours, take out the slices, wash the foam slices with deionized water several times, and then dry them.

[0074] The foam sheet was placed in a silver nanowire solution with a concentration of 0.1 mg / mL, and after soaking for 15 minutes, the foam sheet was taken out and placed in an oven for drying. This step was repeated three times to obtain a foam porous electrode (4) with good conductivity.

[0075] The foam porous electrode (4) is covered on the adhesive layer (3) at a pressure of 10 kPa, and the foam porous electrode (4) is cured at room temperature for 12 hours to complete the bonding of the foam porous electrode (4) to obtain a capacitive flexible pressure-temperature integrated sensor with a stable structure.

[0076] Figure 3 The temperature change curve of the temperature-pressure integrated sensor prepared in this embodiment after ten temperature cycles is shown. After the hot and cold cycles, the response values ​​of the sensor have no obvious attenuation, the difference is small, and the signal attenuation is less than 1%, which proves that this embodiment has good thermal stability and is suitable for temperature measurement.

[0077] Figure 4 The dielectric properties of the integrated temperature and pressure sensor and the pure MXene pressure sensor prepared in this embodiment are demonstrated. At an excitation frequency of 1 kHz, it can be seen that the dielectric constant of the composite is significantly higher than that of pure MXene, up to 17.8 times, ensuring the high sensitivity of the sensor.

[0078] Figure 5The rapid touch test of the temperature and pressure integrated sensor prepared in this embodiment is demonstrated. From the figure, it can be seen that the capacitance value increases rapidly after the touch and can return to the baseline in a short time. It can achieve an extremely high response frequency, a fast response, and very good dynamic performance.

[0079] In summary, the flexible integrated pressure and temperature sensor and its manufacturing method according to the embodiment of the present invention adopt a dual-electrode structure. One end is connected to the GDY / MXene composite film, and the other end is connected to a flexible wire to transmit an electrical signal to an external reading device. In addition, the sensor is covered with a protective layer to increase its durability and stability. The manufacturing process is simple and low in cost, while ensuring the flexibility and durability of the sensor. While realizing the integrated detection of pressure and temperature, the characteristics of GDY / MXene are utilized to ensure high sensitivity and rapid response, and the outstanding structural design is adopted to ensure its excellent flexibility and stability.

[0080] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. Flexible integrated pressure and temperature sensor, characterized in that: It includes: A flexible substrate (1), a sensing material layer (2), an adhesive layer (3), and a foam porous electrode layer (4).

2. The preparation process of the flexible integrated pressure and temperature sensor is characterized in that: The specific steps are as follows: Step 1: Preparation of flexible substrate, selecting a flexible electrode material with a conductive layer on the surface as the sensor substrate; Step 2: Preparation of the sensing layer: Mix the pre-prepared GDY dispersion and MXene dispersion in an appropriate organic solvent to form a uniform mixed solution; The mixed solution is evenly coated on the PDMS substrate by spraying, and then placed in an oven for baking again to ensure the close bonding of the nanocomposite material to the substrate; Step 3: Preparation and connection of adhesive layer: Select appropriate high dielectric constant adhesive material and evenly apply it on the sensing layer to ensure good electrical contact; Step 4: Add a foam electrode layer, cover the sensing layer and adhesive layer with another layer of foam electrode material, and then bake and cure to provide additional flexibility; Step 5: Testing, after manufacturing is completed, the sensor is connected to the test equipment for pressure and temperature response testing to ensure its normal function.

3. The preparation process of the flexible integrated pressure and temperature sensor is characterized by: The PDMS precursor liquid and the curing agent are mixed in a certain ratio, wherein the certain ratio is in the range of 1:2 to 2:

1.

4. The preparation process of the flexible integrated pressure and temperature sensor according to claim 2, characterized in that: The GDY dispersion was prepared by dispersing GDY powder in N-methyl-2-pyridone (NMP) at a concentration of 0.5 mg / mL and ultrasonically treating at 40 kHz for 2 h.

5. The preparation process of the flexible integrated pressure and temperature sensor according to claim 2, characterized in that: The MXene dispersion was prepared by dispersing MXene in N-methyl-2-pyridone (NMP) with a concentration of 0.5 mg / mL.

6. The process for preparing the flexible integrated pressure and temperature sensor according to claim 2, characterized in that: The MXene is prepared by HF acid etching method, and Ti3AlC2 is selected as the precursor material.

7. The preparation process of the flexible integrated pressure and temperature sensor according to claim 2, characterized in that: The content ratio of the GDY dispersion to the MXene dispersion in the composite is 1:

1. Continuous stirring is required during the mixing process. The stirring speed is not higher than 300 r / min and the stirring time is 48 h.

8. The process for preparing the flexible integrated pressure and temperature sensor according to claim 2, characterized in that: The spraying method is ultrasonic spraying, the speed is 0.3mL / min, and the heating temperature is 80°C; In step 4, the baking temperature is 40° C.-70° C., and the baking time is 2 hours.

9. The process for preparing the flexible integrated pressure and temperature sensor according to claim 2, characterized in that: The dielectric constant of the high dielectric constant adhesive layer is not less than 100; The material of the foam porous electrode can be selected from aerogel conductive material, and the porosity of the aerogel conductive material is not less than 0.1% and does not exceed 0.25% at most.

10. The process for preparing the flexible integrated pressure and temperature sensor according to claim 2, characterized in that: The material of the foam porous electrode can be a conductive material with a polymer foam skeleton as the main body, and the porosity of the conductive material with a polymer foam skeleton as the main body is not less than 2% and does not exceed 18% at most; the preparation process of the conductive material is: select a suitable polymer foam as the skeleton, then perform a hydrophilic surface treatment or a roughening treatment on the main body of the conductive material, and finally select a solution impregnation method or an electroless deposition method to prepare a porous polymer foam electrode; The detection step includes the pressure sensing performance of the sensor and the temperature sensing performance of the sensor.

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